Re: SPI Digital Waveform Library

Hi - I'm hoping to use the set of libraries and examples you provide in this thread with a CUI AMT203 absolute position encoder that has an SPI interface. I've read this thread and everything else I can find on the NI website but can't tell if I'll be able to use these .vis with a N-I9401 in a cDAQ-9174 chassis. I know the 9174 has hardware timing but I'd like to double check that the "DAQmx SPI.vi" example is a good place to start with my hardware.

Re: SPI Digital Waveform Library

You shouldn't have problem using the 9174/9401 combination to control your device, but there are a couple of things you have to be aware of:

DAQ devices do not support per cycle tristate. This means that if you are attempting SPI communication on a single data line it would not work. Looking at the module you are using this doesn't seem to be an issue as there are seperate lines for input and output.

Re: SPI Digital Waveform Library

It appears the "slowdown effect" that HF-Walter reported for LV2010 may be caused by the LV8.6 code being recompiled when it is loaded into memory. If you click "Save All" after loading the VIs, these compilation changes should be committed to the VIs, and the dev-time execution speed should be restored to what it was in LV8.6 and LV2009.

On the SPI Digital Waveform Reference Library page, it mentions that "These waveforms can be generated using any National Instruments hardware-timed digital i/o device." So check to see if your device supports hardware-timed Digital IO, and if it does, then you more than likely can use the waveforms that the tool generates with your digital device to communicate with SPI devices. This is also mentioned earlier in this discussion forum, if you glanced through some of the other posts on here. Hope this helps.

Re: SPI Digital Waveform Library

As DJ L pointed out, since the 6133 has Correlated Digital I/O it should run just fine. Are you looking to buy this card? If so we can test it out for you to double check. If you already have this card I'd say go ahead and use it. Please post with your results.

Re: SPI Digital Waveform Library

I have some basic questions about how to use SPI digital waveform library. Can you provide me with detailed explanation on how to set up "SPI timing (ns)" Control input terminal? I want to know the definition of each items in this cluster. Currently, I want to send out some SPI command to my device. CPOL=0, CPHA=1, sample rate is prefered to be 1M. But I don't know how should I fill out other items in "SPI timings", SCLK freq, MOSI setup, SCLK hold, CS lead, CS trail, CS idle, etc.

Can you give me an example of setting up those SPI timing information? Thanks.

Re: SPI Digital Waveform Library

I have a question regarding the SPI timing setting. When I choose to use CPHA=1, namely "format = 1", I found that I have to set MOSI setup time to be smaller than SCLK Assertion time. Even if they are equal, it won't work and no SCLK pulses generated.

For instance, in my program, I set CPHA=1, sample rate = 1M, SCLK frequency = 100K. SCLK hold time = 5000ns, MOSI setup time = 5000ns. LV program does not generate any SCLK pulse. But if I change MOSI setup time = 4500ns, I start to see SCLK pulse. However, DIN changes 1 clock tick after the posedge of SCLK. How can I make DIN change align to the posedge of SCLK, no lag at all? When I look into the block digram of "init.vi", it requires (SCLK period - SCLK hold time) greater or equal to MOSI setup time. So why when I set these two timings equal, I don't see any SCLK pulse?